I've noticed the last couple of years that here in my locale it doesn't really exist.
The hawthorn is just finishing & the sycamore not long over & already a reasonable amount of white clover & bramble in evidence.
What is it like with your bees?

I think if you have gardens or wild areas round you its fine. Its the large fields under cultivation that are problems I think. We have been surrounded on 2 sides (since we moved here) with acres of miscanthus, so we only have cropping fields on 2 sides. This year its wheat, last year spuds, so not particularly helpful. I really a lot on tree pollen & nectar, so small fields with hedges is really important.
I cut & laid our perimeter hedge this winter, but its been blooming again with sloe and Ive planted a lot of rosemary & daisy type plants. I could never sustain more than 2 colonies here, mainly because of lack of forage.

Interesting you are both in Cornwall, I am in Surrey and my bees are in my suburban back garden. I agree more with Tav, the gardens are flowering well, hedges are just finishing, Clover and brambles are flourishing and lots of trees nearby.

Think it will depend on where you are. The best places for bees these days is in town because of all the garden flowers. The OSR is over by June and they haven't grown any spring rape, which used to give us a good crop, for years, but we do get wild raspberry and then bramble flowers for our bees in the woods.

the best place for a lot of "common"wildlife is urban gardens,they provide year round food(inc supplements from bird tables,bin bags,kebab droppings etc, etc)and many folk have reduced or stopped using pesticides,there are a variety of niches to live in .

an industrial agricultural landscape is built to favour a monoculture of a crop and wildlife is a pest or bycatch of pest control

There's no June gap here. The hedges around the farm have been planted with dog roses which are covered in flowers at the moment, brambles are out and there is so much honeysuckle along the lanes that the car smelt sweetly of it as I drove along. The fields are full of flowers and then there is gorse of course.

I was told by my beekeeping instructor that honey bees cannot sup from honeysuckle, as their tongues are not long enough to reach the nectar.

Gorse is mostly good for pollen.

EB Wedmore a Manual for Bee-Keeping, has tables in it of what plants are good for nectar, which are minor but useful and which is pollen only. Very useful.

This is what I was led to believe as well.
Wedmores book is a useful reference for many things.
Honey bees will take advantage of some of the deeper flowers by following one of the small bumble species that eats a hole at the base of the flower to reach the nectar.
I've seen my bees do this on runner bean flowers.
Sorry Dpack replied to muttons post before I read yours.

It is quite common for bumble bees to chew a hole in bean flowers to get at the nectar. The honey bees can then access the flowers. It also depends upon rain fall. Buddleia is useful for bees if it has been raining a lot as the tube fills with nectar, but goes down in dryer weather so only moths and butterflies can access it.